Anthony A. Raviele

Importance of acquired systemic-to-pulmonary collaterals in the Fontan operation

BACKGROUND Children with chronic cyanotic heart disease often develop systemic-to-pulmonary collateral arteries that can be deleterious at the time of a Fontan procedure due to excessive pulmonary blood flow. We therefore occlude all significant collaterals during cardiac catheterization. METHODS From June 1993 to May 1998, 93 children aged 1.5 to 15.8 years (median 2.5 years) underwent a fenestrated lateral tunnel Fontan procedure. Eighty-nine (96%) had a previous bidirectional Glenn anastomosis, including 31 (33%) with a Norwood procedure. RESULTS Preoperatively, 33 children (35%) required occlusion of 1 to 11 (mean 3.6) collateral vessels. Two of the three perioperative deaths (operative survival 97%) were due to excessive pulmonary blood flow from unrecognized collaterals in one and uncontrollable collaterals in the other. Postoperatively, 19 children (20%) required coil occlusion of 1 to 21 (mean 5.6) collaterals for elevated pulmonary artery pressures, heart failure, or prolonged chest tube drainage. Duration of inotropic support, postoperative ventilation, intensive care unit stay, and postoperative hospitalization were all significantly longer in the patients who had postoperative occlusion of collaterals. On follow-up of 2 to 67 months (mean 35 months), there have been four late deaths (two infections, two heart failures); 6 patients underwent successful cardiac transplantation for refractory heart failure. All 8 patients with ventricular failure required occlusion of significant collaterals postoperatively. CONCLUSIONS Hemodynamically significant collaterals are not uncommon in Fontan candidates, and aggressive control can result in good operative and medium-term survival. After the Fontan, significant collaterals may be a marker for eventual cardiac failure because 8 of 18 patients requiring postoperative coils went on to transplantation or died of heart failure.

Current results with pediatric heart transplantation

BACKGROUND Cardiac transplantation is an accepted treatment for children with end-stage heart failure or complex or inoperable congenital defects. METHODS Since 1988, 95 transplants have been performed in 89 children aged 4 days to 18 years (median 6.9 years, 42 patients 0-5 years). Fifty-eight (61%) had congenital or acquired heart disease, 31 (33%) had idiopathic cardiomyopathy, and 6 (6%) were retransplants. Fifty-seven of the patients had prior cardiac surgery with a range of one to eight procedures (mean 3.4 procedures/patient). At the time of transplantation, 53 (56%) were United Network for Organ Sharing (UNOS) status I, including 23 children on mechanical ventilation and 4 with mechanical circulatory support. RESULTS Thirty-day survival in this group was 96%. Posttransplant results showed a median time of ventilation of 1 day (mean 3.0+/-5.7 days), median duration of inotropic support of 2 days (mean 2.7+/-2.3 days), median intensive care unit (ICU) stay of 4 days (mean 6.9+/-9.6 days), and median hospitalization of 9 days (mean 14.3+/-13.9 days). Follow-up from 1 month to 10.3 years (mean 3.1 years) has demonstrated a 1-year actuarial survival of 79% and a 5-year actuarial survival of 69%. Rejection, both acute and chronic, accounted for the vast majority of deaths. CONCLUSIONS Pediatric heart transplantation can be accomplished with excellent early survival despite multiple prior cardiac operations and relative severity of illness. Parameters such as postoperative ventilation, inotropic support, ICU stay, and hospitalization can be kept at reasonable levels with acceptable long-term results, although rejection remains a serious problem.

Saphenous vein homograft: a superior conduit for the systemic arterial shunt in the Norwood operation

BACKGROUND Excessive pulmonary blood flow increases ventricular volume work in the face of inadequate systemic cardiac output, low diastolic blood pressure, and inadequate coronary perfusion. Using the smallest available 3-mm polytetrafluoroethylene shunts have been successful, although catastrophic shunt thrombosis has occasionally been observed. To avoid thrombosis with a smaller conduit, saphenous vein homografts (SVG) were used to construct the modified Blalock-Taussig (BT) shunts. METHODS From January 1998 to April 1999, 25 patients weighing 3.1 kg (3.0 kg or less, n = 9), at a mean age of 8.9 days, underwent stage I Norwood using an SVG BT shunt. Common heart defects were aortic atresia (n = 8), mitral atresia and double-outlet right ventricle (n = 5), and unbalanced AVC (n = 5). Mean BT shunt size was 3.2 mm, with 12 patients having shunts that were 3 mm or smaller. RESULTS Thirty-day hospital mortality was 8% (2 of 25). No shunt thrombosis was seen, despite banding the BT shunt in 3 patients. One patient had BT revision because of an anatomic issue not directly related to the shunt material. CONCLUSIONS Excellent results may be achieved using SVG BT shunts in the Norwood operation. This conduit seems less likely to thrombose, both acutely and chronically, allowing the use of appropriately smaller-sized shunts in small neonates.

Occlusion of the Modified Blalock–Taussig Shunt: Unique Methods of Treatment and Review of Catheter‐based Intervention

OBJECTIVE To report unique methods of treatment and review catheter-based intervention for occluded modified Blalock-Taussig shunts (BTS). METHODS Case reports and articles involving children undergoing catheter-based treatment for occluded modified BTS were reviewed. RESULTS Literature review detailed 38 patients in whom occluded modified BTS were treated with 39 catheter-based interventions. Thrombolytics alone were delivered by catheter in 13 cases. Balloon angioplasty was performed in 23 cases, 5 with stent implantation. Both thrombolytic delivery and angioplasty were performed in 3 cases, 2 with stent implantation. Intervention was initially successful at re-establishing modified BTS patency in 35/39 (90%) of cases. Patency could not be established in 2 patients who then proceeded to the operating for surgical shunt revision. Two deaths occurred during the procedures. Three cases at Emory University demonstrate uncommon or unique instances of catheter-based intervention: (1) declotting of a shunt in a patient supported by extracorporeal membrane oxygenation (ECMO); (2) declotting of a shunt via a right axillary arterial approach; and (3) declotting of a shunt using a carotid arterial (ECMO) cannula for percutaneous access. CONCLUSIONS The use of catheter-based techniques for the treatment of BTS occlusion is highly successful, and potentially avoids high-risk re-operative intervention. ECMO can provide for a stable patient during the procedure. Hopefully, with improved technology and innovative procedures, more children in the future with BTS occlusion can be served by successful percutaneous intervention.

Experience with a Low Profile Bipolar, Active Fixation Pacing Lead in Pediatric Patients

Continued miniaturization of permanent pacing systems has promoted use of this technology in younger and smaller pediatric patients. Intermedics ThinLine 438–10 active fixation pacing leads (4.5 Fr lead body) were implanted in 26 patients (17 males/9 females; 9.9 ± 6.9 years). Twenty of 26 patients received dual chamber systems, 6 of 26 patients single lead systems. Each patient has been followed3 3 months. Pacemaker analysis at implant and 6 months later evaluated pulse width thresholds at 2.5 V (atrial 0.07 ± 0.02 vs 0.13 ± 0.02 ms [P = 0.01]; ventricular 0.08 ± 0.04 ms vs 0.20 ± 0.04 ms [P = 0.01]); sensing thresholds (atrial 4.1 ± 0.41 mV vs 4.0 ± 4.2 mV [P = NS]; ventricular 9.7 ± 0.72 vs 9.3 ± 0.94 mV [P = NS]); and impedance (atrial 345 ± 12 vs 370 ± 120 O [P = 0.04]; ventricular 412 ± 17 vs 458 ± 190 O [P < 0.01]). One volt lead failed with exit block at approximately 6 weeks. The youngest (9 months to 5 years) and smallest (6.5–18.0 kg) ten patients have each shown by venography to have at least mild venous stenosis at the lead(s) insertion site; five patients demonstrated collateral formation around asymptomatic obstruction, with no thrombus formation. The Intermedics 438–10 ThinLine pacing lead has demonstrated good and stable early postimplant electrical parameters. Angiographic evaluation in our smaller patients has shown evidence for asymptomatic venous obstruction.

Transcatheter closure of secundum atrial septal defect in infants less than 12 months of age improves symptoms of chronic lung disease.

OBJECTIVE   Device closure of secundum type atrial septal defects in young children has now become common with extension of this practice to children less than 1 year of age. We hypothesized that patients less than 12 months of age with moderate increases in pulmonary blood flow due to atrial septal defects may improve clinically with device closure, particularly premature infants with chronic lung disease. DESIGN   Thirteen patients under 12 months of age have undergone atrial septal device closure at our institution from March 2002 to July 2008, with evidence of a left to right shunt by pre-procedural echocardiogram. We evaluated concomitant conditions and device closure results. Patient charts from follow-up visits with referring pediatric cardiologists were also reviewed. Follow-up phone interviews were conducted with parents/guardians of patients who underwent device closure to further evaluate clinical change. RESULTS   The patient ages ranged from 3-11 months (median 7) with weight ranges of 2.9-8.3 kg (median 6.5). Defect sizes ranged from 5-15 mm (median 9). Concomitant conditions included prematurity with bronchopulmonary dysplasia (n = 8) and concern of elevated pulmonary artery pressures (n = 5). The median Qp : Qs was 1.6 with a range of 1 to 2.6. The mean pulmonary artery pressures ranged from 16 to 55 mm Hg (median 27). Eleven of 13 patients showed significant improvement in their clinical status, with a reduction in oxygen requirement (six patients) and reduced right heart pressures by echocardiogram (four patients). There were no residual defects on follow-up echocardiograms. CONCLUSION   Transcatheter closure of atrial septal defects in infants can be safe, effective, and may be indicated for situations in which the left to right shunt may be implicated as a cause of ongoing chronic lung disease. Moderate increases in pulmonary blood flow due to atrial septal defects may have a negative clinical impact regarding continuing respiratory insufficiency in these patients.

Use of a 3 French system for balloon aortic valvuloplasty in infants

For infants with valvar aortic stenosis, balloon aortic valvuloplasty has supplanted surgical valvotomy as the initial treatment of choice at most institutions. Technological innovations have resulted in further miniaturization of balloon dilation catheters, allowing this procedure to be performed through smaller sheath sizes. Currently, the Tyshak‐Mini balloon dilation catheter (B. Braun Medical) allows passage of up to an 8 mm dilation balloon catheter through a 3 Fr hemostatic sheath. The efficacy of this system for the treatment of valvar aortic stenosis in infants less than 6 months of age was evaluated in 20 patients undergoing 22 procedures. Mean age at the time of intervention was 26 ± 46 days. Mean transvalvar gradient was 76 ± 22 mm Hg prior to balloon dilation. Following balloon valvuloplasty, residual gradient was 26 ± 12 mm Hg, reflecting a mean change in peak‐to‐peak gradient of 49 ± 19 mm Hg. Postintervention increase in aortic insufficiency was one grade or less in 19/22 procedures, two grades in 2 procedures, and three grades in 1 procedure. There were no significant vascular complications reported immediately following the procedure. Repeat valvuloplasty was performed in three patients in which the 3 Fr system was used in two patients. The 3 Fr system for balloon aortic valvuloplasty in infants less than 6 months of age is effective and safe.